Identify the incorrect statement from the following:

1.	Zirconium and Hafnium have identical radii of 160 pm and 159 pm, respectively as a consequence of lanthanoid contraction.
2.	Lanthanoids reveal only +3 oxidation state.
3.	The lanthanoid ions other than the f0 type and the f14 type are all paramagnetic.
4.	The overall decrease in atomic and ionic radii from lanthanum to lutetium is called lanthanoid contraction.

Match the following aspects with the respective metal:

Select the correct option:

The catalytic activity of transition metals and their compounds is ascribed mainly to:

1. their unfilled d-orbitals
2. their ability to adopt variable oxidation states
3. their chemical reactivity
4. their magnetic behaviour

Which one of the following does not correctly represent the correct order of the property indicated against it?

Lanthanoid's most common oxidation state is:
1. 2
2. 5 
3. 3 
4. 4

Which of the following exhibits only a +3 oxidation state?

Four successive members of the first series of the transition metals are listed below. For which one of them does the standard potential $\left(E{°}_{M^{2+}/M}\right)$ value have a positive sign?
1.  Ni (Z = 28)
2.  Cu (Z = 29)
3.  Fe (Z = 26)
4.  Co (Z = 27)

The aqueous solution containing which one of the following ions will be colourless:

1. Fe²⁺

2. Mn²⁺

3. Ti³⁺

4. Sc³⁺

[Atomic number : Sc = 21, Fe = 26, Ti = 24, Mn = 25]

Four successive members of the first-row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionization enthalpy:

1. Vanadium (Z = 23)

2. Manganese (Z = 25)

3. Chromium (Z = 24)

4. Iron (Z = 26)

Colourless ion among the following is: